Process for improving the properties of water-insoluble artificial protein fibres



Patented Sept. 2, 1947 UNITED STATESPATENT OFFICE PROCESS FOR IMPROVING THE PROPER.

TIES OF WATER-INSOLUBLE ARTIFICIAL PROTEIN FIBRES Giampiero Comolli, Milan, Italy, assig'nor to Sandoz A. G., Basel, Switzerland No Drawing. Application November 8, 1939. Serial No. 303,158. In Italy November 14, 1938 pounds, there is a very appreciable improvement in the dynamometric resistance of the fibre itself (in the moist as well as in the dry state),

in the resistance to fulling, friction and wear,'

in the resistance to the action of boiling water even in the presence of acid or alkali and also in the resistance to the action of hot iron (ironing), and thereis also an increase in the fastness of the dyeings produced thereon with acid dyestufis and chrome dyestufls as well as with direct dyestufis and dyestufis belonging to other categories.

The artificial fibre, when subjected to the treatment hereinafter described, undergoes an action similar to the action produced on depilated skins when subjected to chrome tanning with one or two immersions, which acquire great tenacity and powerful resistance to stretching and are not affected by boiling water.

This treatment enables, furthermore. the above-mentioned artificial fibres to absorb and retain dyestuffs in a much higher condition of stability than is the case with artificial fibres obtained from protein-Hike material not subjected to the process which forms the subject matter of the patent. In fact, acid dyestufis which when applied on untreated fibres do not resist even light washing, on the contrary after treatment according to the present invention they withstand very well washing at 60C. in presence of soap and carbonate of soda; Moreover, the

treatment in question makes it possible to dye ,with all chrome dyestuffs generally without impairing the resistance of the artificial fibre, contrary to what happens in the case of dyed fibres obtained from protein-like substances and not treated by the process which forms the subject matter of this invention.

The treatment which is covered by this invention and can be used in the actual manufacture of artificial fibres formed of or containing protein-like substances, is based on the use of salts of chromium (chrome alum, chromium sulphate,

chromium chloride, etc., either normal or of vari-- ous degrees of basicity). Ii desired the treatment may be effected with two baths, the first containing for example sodium or potassium bichromate and the other containing products capable of converting the compounds of chromic anhydride into compounds of chromium sesquioxide.

In the preparation of this second bath the following compounds can be used:

(a) Sodium thiosulphate, sodium bisulphite, sulphurous acid and its derivatives or any other reducing means or substance.

(b) Any oxidising means or substance capable of converting chromic acid into perchromic acid which, owing to its instability. can produce compounds of chromium sesquioxide.

The following examples illustrate how the invention may be carried out in practice, but it is to be understood that the invention is in no way limited by the details given in these examples.

Example 1 Artificial fibre prepared from casein is impregnated in a bath containing grams per litre of potassium bichromate with the addition, if desired, of a mineral acid. After the impregnation of the fibre it is squeezed and placed in another bath containing 100 grams per litre of sodium bisulphite and then thoroughly washed with water. The fibre so treated acquires all the properties above mentioned (better resistance to stretching, wear, boiling water, etc.).

Example 2 Artificial fibre treated as in Example 1 is dyed with chrome dyes by the afterchroming process as well as in the dyeing process with a single bath.

The alkaline iulling of the dyed material does not exercise any negative influence upon the shade and the resistance of the fibres, whilst similar dyeings executed on untreated fibre are practically unusable after having been subjected to alkaline fulling.

. fully washed out.

acaaem Example 4 Artificial casein fibre is soaked in a 10% aque-. ous sodium bichromate solution at 35 C. until bisulphite, the sodium hydrosulphite, thiosulphate or gaseous sulphurous acid mixed with steam.

' Example 100 parts or casin staple fibres are treated in a milling drum during minutes with a 30-40" C. warm solution of 8.10.D ,s of sodiumor potassium bichromate in 400-500 parts of water.

,Thereon-4 parts of hydrochloric acid or a corresponding quantity of sulphuric'acid are added thereto in order to liberate the chromic acid.

. After 20 minutes the major part of the chromic acid has been taken up by. the fibre and the solution is coloured only weakly yellow. For the reduction, thereis added a solution of 12-45 parts of sodium bisulphite and the drum allowed to run until the green solution becomes almost colorless. The fibres are then'rinsed, treated with some ammonia or another alkali like soda, etc., in order to neutralize the free acid, and care- Eaiample 6 The textile material subjected to suchtreatment can then be dyed with any desired dyestuffs. Acid and chrome dyestufi's dye casein and animal fibres, whereassubstantive dyestufl's dye casein and cellulosic fibres; therefore, any desiredcombination of shade may be produced.

The textile materlaltreated and dyed according to the example possesses a much better touch and better dynamometric properties as compared with the material that has not been subjected to the tanning operation.

Example 7 100 parts of casein yam are treated during 18 hours at ?"C. in a solution of the following composition:

Parts Water '1000 Chrome alum 120' Anhydrous sodium carbonate 12 and if necessary 3 partsof a wetting agent which is resistant to chrome salts. j

After this treatment the yarn is hydroextracted, washed out, treated during 21 minutes in 1000 parts of water containing 2 parts of concentrated ammonia, washed again, hydroextracted and dried.

The casein fibre which is colored in a clear olive green shade possesses a smooth touch which remains, even after a subsequent dyeing in a bath containing mineral acid. The resistance to breaking and the elasticity of the casein fibre treated in this manner is much better as compared with the casein fibre which has not been subjected to the above treatment.

What I claim is:

1. A process for producin water-insoluble artificial casein fiber, which comprises the steps of impregnating hardened fiber, prepared from a casein solution by a spinnin and hardening process, with a solution of a water-soluble chromium'compound, and then converting the latter,

into a. water-insoluble chromium compound by treatment of the impregnated fiber with a reducing agent, thereby causing the formation and fixation of the water-insolubl chromium compound in and on the treated fiber.

2. A process for producing water-insoluble artificial casein fiber, which comprises the steps of impregnating hardened fiber, prepared from a casein solution by a spinning and hardening process, with a solution of a water-soluble salt of chromic acid, and then converting the latter into a water-insolubble chromium compound by treatment of the impregnated fiber with a reducing agent, thereby causing the formation and fixation of the water-insoluble chromium compound in and on the treated fiber. I

3. A process for producing water-insoluble artificial casein fiber, which comprises the steps of impregnating hardened fiber, prepared from acaseln solution by a spinning and hardening process, with a solution of a water-soluble salt 'of chromic acid, and then treating the impregnated fiber with a solution of a reducing agent.

4. A process for producing water-insoluble artificial casein fiber, which comprises the steps of impregnating hardened fiber, prepared from a casein solution by a spinning and hardening process, with a solution of an alkali metal bichromate, and then treatin the impregnated fiber with a solution of an alkali metal bisulphite.

5. Water-insoluble artificial casein fiber comprising an insolubilized fiber body prepared from a casein solution by a spinning and hardening process, and containing a subsequently-incorporated water-insoluble chromium compound in and on said fiber body, said fiber possessing improved dynamometric resistance and improved fastness to boiling water, milling, washing and dyeing, as compared with the same insolubilized artificial fiber free from said water-insoluble chromium compound.

GIAMPIERO COMOLLI.

REFERENCES crr n The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 77,990 Lowrey May 19, 1868 625,345 Millar Oct. 15, 1898 836,788 Todtenhaupt Nov. 2'7, 1906 950,435 Chavassieu Feb. 22, 1910 1,865,497 Atwood July 5, 1932 2,103,163 Lange Dec. 21, 1937 2,120,851 1 Becker et al June 14, 1938 2,140,274 Whittier et a1 Dec. 13, 1938 2,169,955 oosterbeek et a1. Aug, 15, 1939 1,968,991 Clickner Aug. 7, 1934 2,046,320 Burbank July 7, 1936 FOREIGN PATENTS Number Country Date 467,812 Great Britain June 22, 1937 372,271 Italy June 22, 1939 France Nov. 29, 1905 

